CN101118289A

CN101118289A - Electromagnetic surveying

Info

Publication number: CN101118289A
Application number: CNA2007101122449A
Authority: CN
Inventors: 詹姆斯·米尔恩; 詹妮弗·拉斯特; 克里斯·赛克斯; 马克·贝内特
Original assignee: OHM Ltd
Current assignee: OHM Ltd
Priority date: 2004-07-02
Filing date: 2005-05-26
Publication date: 2008-02-06
Anticipated expiration: 2025-05-26
Also published as: AU2005253638A1; RU2434252C2; MX2007000309A; EP1771750B1; US7683625B2; AU2007202514A1; AU2005253638A8; EP1771750A1; BRPI0505980A; GB0618123D0; EP1830201A2; DK1771750T3; GB2415785A; AU2005253638B2; ATE411540T1; RU2346298C2; DE602005010437D1; GB2415785B; GB2427482A; NO20060460L

Abstract

A submersible electromagnetic (EM) field generator for seafloor electromagnetic surveying comprising an AC to DC converter operable to generate a DC output from an AC input and a switching module operable to generate a waveform driving signal by selectively switching the DC output. The EM field generator also comprises an antenna that is operable to generate an EM field in response to the waveform driving signal. This design approach of using a switched DC source allows square or rectangular wave EM signals to be generated which have sharp transition characteristics and which are substantially independent of the AC input characteristics.

Description

Electromagnetic survey

Present patent application be priority date be July 2, international filing date in 2004 be May 26, international application no in 2005 be 200580000617.2 for PCT/GB2005/002129, national applications number, denomination of invention divides an application for the application for a patent for invention of " electromagnetic survey ", it all is incorporated herein by reference at this.

Technical field

The present invention relates to electromagnetic survey.The invention particularly relates to the generation of exploration oil and gas reservoir or other electromagnetism (EM) can be by their stratum of electrical characteristics identification the time.

Background technology

Determine that in the geophysical reconnaissance field subsurface formations in the earth's crust is a kind of valuable instrument to the response of electromagnetic field.Can study the geological process that occurs in heat, hydrothermal solution or the magnetic acitvity district.In addition, under the environment that underground petroleum is detected and explored electromagnetism probing technology can provide usefulness to state of nature and especially to the understanding of possible hydrocarbon content.

In investigating, oil-exploration adopts traditional seismic technology so that determine existence, position and the scope of reservoir in the subterranean strata.Although seismic prospecting can be discerned this structure, this technology usually can not be distinguished the possible heterogeneity of these structure mesoporosity fluids, especially when pore fluid has similar engineering properties.

Although oil-filled mechanically similar with reservoir water-filling, they have visibly different by other electrical characteristics of active (active) EM exploration area.Initiatively the EM exploration produces the EM field based on the suitable EM source that utilization is positioned adjacent to the seabed.Then propagate by the diffusion of passing subsurface formations and measure by the remote receiver that is arranged on seabed on the seabed or close from the energy in this source.Term " initiatively " is used for distinguishing the passive EM technology of mt (MT) exploration, and the latter measures the response of subsurface formations to the spontaneous EM of earth top atmosphere field.

Initiatively the employed standard EM of EM source is the electric dipole antenna that stretches out from the traction submarine, and this traction submarine is commonly referred to tractor tug (UTV) or drone (ROV) under water, below uses a back title.By promptly driving electric dipole from the suitable electrical waveform that provides waterborne from survey vessel.Owing to pass the diffusion EM signal strong attenuation that subsurface formations is propagated, cause a little less than the signal that detecting device receives, thereby be important for EM source high power.For generation the antenna of force signal is arranged, ROV must be by transmission cable from reception high power signals waterborne.The conventional difficulty that then applies this electric signal along cable transmission high power electric signal is loss, timing drift, impedance matching or the like.

A kind of Known designs [1] is used alternator and stepup transformer on the water and electrical waveform is converted to high voltage/low current signal for from the ROV of being transferred to waterborne, thereby reduces the loss on the cable.After being transferred to ROV, this high voltage/low current signal converts low-voltage/high current signal again to and then is used for driving streamed antenna.This streamed antenna comprise two along the length of antenna at interval electrode and separate each other by seawater in not having entry the time.But although seawater provides the current flow path between the electrode, seawater also provides the load of high perception in essence.In fact, this proves problematic, is to produce the voltage transient that can damage the components and parts in the drive waveform signal source because the high perception of this load causes generation back-emf, the effect of this back-emf when switch current.

Desirable initiatively another important design criteria in EM source is the waveform that can produce.Desirable EM source should be able to produce any arbitrary function form.In fact, square wave (or square wave) is a kind of important shape that can produce.The interested high-order harmonic wave of being not only its fundamental frequency and comprising its generation is as understanding from the Fourier expansion of square wave.In other words, square wave source can be used as the use of multifrequency source.Thereby importantly can produce the amplitude of good definition and the regular square wave of timing standard.

These known cyclic converter parts [1] are operable to, and on the cycle of predetermined quantity the AC wave shape of input are carried out full-wave rectification to produce the positive polarity full-wave rectified waveform of two frequencys multiplication.After producing positive polarity full-wave rectified waveform, on the cycle of other predetermined quantities, put upside down commutating pole to produce the negative polarity current waveform in full-wave rectifier of two frequencys multiplication.Positive and negative polarity current waveform in full-wave rectifier provides approximate square-wave waveform together.

By detecting the zero passage that occurs in the AC wave shape of importing and being counted, the cycle that can carry out commutating pole on the multiple half-wavelength of input exchange signal switches, thereby the corresponding square wave approximate waveform of AC wave shape of fundamental frequency and input is provided.This square wave approximate waveform has two dominant frequency component, and the low fundamental component of polarity switching frequency correspondence, and is the high fdrequency component of the multiple of the AC signal frequency of input that is:.

By widely with the use of success, the restriction of clear known cyclic converter design.The phase place and the variation on the amplitude of the AC signal that antenna produces are undesirable.These problems appear mainly due to from drift and the variable attenuation during ROV transmission AC signal waterborne.The last polarity switching timing of ROV depends on the phase stability of this AC signal, and it can weakened by perception and capacitive effect from downward transmission waterborne.For example, the degeneration of this AC signal can produce wrong zero crossing or cause and do not detect true zero crossing, this so that cause at incorrect time trigger polarity handover event.Therefore, our structure is, the valid function of cyclic converter needs its AC signal of providing of subtend to carry out good stable control, and relaxes any unstable effect that the additional design characteristic among the ROV causes as much as possible.In addition, square wave approximate in from just to negative and from the negative frequency that depends on the AC signal of being supplied with to positive polarity transition period.This guides our design specialist high frequency to produce equipment so that thereby the fast driving cyclic converter shortens transition period.

Summary of the invention

According to a first aspect of the present invention, a kind of diving electromagnetism (EM) field generator that is used for the seabed electromagnetic survey is provided, comprising:

-can be operable to from AC input produce first and second DC output as the AC of positive DC signal in the described first and second DC outputs and negative DC signal to the DC converter;

-can be operable to by optionally switching the handover module that described first and second DC output produces the drive waveform signal, described handover module comprises first switch that is connected on separately between described first and second DC output to right with second switch, each switch between the tie point place the first and second waveform output electrodes are provided; And

-by the antenna that the electrode pair on the respective electrode that is connected to the waveform output electrode forms, it can be operable to this drive waveform signal of response and produce the EM field.

By producing the drive waveform signal, not only provide the approximate square wave that has steep transition characteristic, and the drive waveform signal is irrelevant with the characteristic of AC input basically from DC output.In addition, utilize the diving electromagnetic field generator on this design ROV not need to drive by the special-purpose high frequency power source in the marine equipment.The field generator that for example, should be with ROV be the base can be by being arranged on standard ship waterborne with 50/60 hertz of power drives.

According to a second aspect of the present invention, provide a kind of electromagnetism (EM) generation system that is used for the seabed electromagnetic survey.This EM field generation system comprises the diving electromagnetic field generator according to a first aspect of the present invention, the power supply that is connected to the DC converter with the AC of this electromagnetic field generator can be operable to, and the control module that is connected with the controller of this diving electromagnetic field generator can be operable to.This control module can be operable to the drive waveform signal of controlling and driving antenna.

This control module can be positioned on the waterborne vessel and be used for the EM field that remote control diving electromagnetic field generator produces.This then can produce EM field under the sea that has known and/or variable distribution and the generation of permission EM field and this control module of being positioned on the sea synchronous.

In various embodiments, this control module itself can be operable to gps receiver and be connected, thus allow controller coordinate EM waterborne field to generate and the stratum, seabed on to the measurement of EM field effect.This controller waterborne can encourage this control module and and the Absolute Time Synchronization of GPS transmitter indication obtain having time stamp the EM phase survey measurement data.

According to a third aspect of the present invention, the method for electromagnetism (EM) that a kind of generation is used for the seabed electromagnetic survey is provided, comprising:

-AC is provided signal;

-produce first and second DC output as positive DC signal in the described first and second DC outputs and negative DC signal from this AC signal;

-by using first switch to producing the drive waveform signal to optionally switching described positive DC signal and negative DC signal with second switch, described first switch to and second switch to being connected in series in separately between described first and second DC output, each switch between the tie point place the first and second waveform output electrodes are provided; And

-utilize this drive waveform signal to drive the eelctric dipole that forms by the electrode pair on the respective electrode that is connected to the waveform output electrode to be produced the EM field.

Description of drawings

In order to understand the present invention better and to show and in fact how to realize the present invention, now as an example with reference to each accompanying drawing, in the accompanying drawing:

Fig. 1 illustrates the sea floor exploration system that comprises according to the diving EM field generator of one embodiment of the invention;

Fig. 2 is illustrated in the AC that uses in the diving EM field generator according to one embodiment of the invention to DC converter and handover module;

Fig. 3 is illustrated in handover module and the transient suppressor that uses in the diving EM field generator according to one embodiment of the invention;

Fig. 4 schematically illustrates the EM field generation system that is used for according to the seabed electromagnetic survey of one embodiment of the invention; And

Fig. 5 schematically illustrates the drive waveform signal by the diving EM field generator generation of foundation one embodiment of the invention.

Embodiment

Fig. 1 illustrates the sea floor exploration system 1 that comprises diving EM field generator 5.EM field generator 5 is carried by the underwater ship 12 by waterborne vessel 4 tractions.12 pairs of seabeds of underwater ship 22 keep the distance of almost fixed.This spacing be by the distance of measuring 12 ends off sea of underwater ship and the echolocation module 14 that the information about the spacing that measures is forwarded to waterborne vessel 14 reached.Then can be by stube cable 10 being rolled up the degree of depth that is put into suitable length or adjusts underwater ship 12 by alternate manner (for example utilizing boat-carrying thruster and/or hydrodynamic force surface control underwater ship 12).

Send energy and control signal from waterborne vessel 4 to underwater ship 12 by stube cable 10, this cable also provides the mechanical linkages between waterborne vessel 4 and the underwater ship 12.EM field generator 5 utilizes these energy signals and control signal to produce through the EM field of seabed 22 injection in the extra

large sub-surface

24,26.

The reciprocation of this EM field and extra

large sub-surface

24,26 produces the EM field signal.This EM field signal is carrying the information of the composition of relevant extra

large sub-surface

24,26, and they can be used to discern the type of the liquid that contains in the stratum, carrier fluid seabed 26.By detect the component of this EM field signal with a certain distance from one or more receiving antennas 28 of underwater ship 12.Directly transmit EM field between high conduction seawater strong attenuation EM field generator 5 and the receiving antenna 28, can ignore the contribution of this component to the EM field signal that receives under the situation of hundreds of rice thereby spacing surpasses.

Typically, receiving antenna 28 arrays or graticule mesh are set, wherein each receiving antenna is positioned on each precalculated position in seabed 22.Each receiving antenna 28 can be operable to separately long-range set of equipments 30 and floating member 32 that can long-range expansion and be connected.Long-range set of equipments 30 records and the corresponding data of receiving antenna 28 detected FM field signals.Before being deployed on the seabed 22, clock in the long-range set of equipments 30 and the major clock (not shown) on the waterborne vessel are synchronous.In case finish the EM exploration, send the remotely stimulating signal from ship 4 waterborne to extensible floating member 32, thereby launch them and long-range set of equipments 30 is risen on the sea level for recovery.In case reclaim, can analyze data at leisure from long-range set of equipments 30.

EM field generator 5 comprises AC to DC converter 18, handover module 19 and antenna 20.AC provides DC output to 18 pairs of handover modules 19 of DC converter.Generate drive waveform signal by switching various DC level handover modules 19 to antenna 20.For example, can switch the positive dc voltage that zero voltage level is followed in the back, to approach the square wave formula drive waveform signal of one-period to antenna.

Send AC input to the AC of EM field generator 5 to DC converter 18 from the power supply on the ship waterborne 6 by stube cable 10.For example, power supply 6 can produce 50 or 60 hertz three-phase sine-wave with 4500 volts of peak to peak voltages.Power transmits to adopt high voltage AC can reach efficiently between power supply 6 and EM field generator 5.In addition, power supply 6 can be a three phase generator and pass through whole three the electric power phases of stube cable 10 transmissions.Adopt this three-phase supply not only to improve power conversion efficiency, can also be used to hanging down pulsation DC to 18 outputs of DC converter from the AC that utilizes less device to constitute.By adopting than the more minimizing that can further improve pulsation mutually of three-phase.

Control module 8 by being arranged in ship 4 waterborne produces control signals and the optical fiber link by stube cable 10 sends to the controller 16 that is arranged in underwater ship 12.Adopt the benefit of optical fiber link to be, it provides the little constant transmissions stand-by period that control signal generates and controller 16 receives between this signal on the ship 4 waterborne.Control module 8 can be operable to gps receiver 3 and be connected.Gps receiver 3 receives the GPS timing signal that sends from satellite-based GPS transmitter 2.Based on these GPS timing signal and internal electronics, control module 8 can produce the timing signal that is comprising high frequency clock signal (for example 1024 hertz) and low-frequency clock signal (for example pulse signal or the burst of per minute transmission).Control module 8 sends to controller 16 to these clock signals.

Have the control module 8 of gps receiver 3 by employing, remotely synchronous operation controller 16 with respect to the GPS timing signal known the time engrave and produce the drive waveform signal.In addition, can carry out data aggregation by controller 16, and utilize the accurate time stamp that gps time is produced, the data point of collecting on the underwater ship 12 can be the data with time stamp.And the time stamp signal of the absolute time in the time of can modulating the EM field signal and generate to comprise indication EM field signal comprises being positioned at the requirement of the synchronous accurate clock of control module 8 on the ship 4 waterborne thereby reduce long-range set of equipments 28.Can be by long-range set of equipments 28 record time stamp signals and when analyzing data so that determining kind of liquid in the carrier fluid stratum 26, use subsequently.

Although should be understood that and specifically noted for convenience and can alternatively use the clock signal of other wireless transmission by GPS, can obtain them if can obtain them or become in the future.These signals can be from land signal station or based on satellite.For example, base in the time of can being used as mobile telephone signal for the coastal waters.

In addition, control module 8 can send command signal to controller 16.These command signal indicating control 16 operation handover modules are to produce various drive waveform signals.For example, these command signals can select to have the specific waveforms drive signal of various frequency, mark-to-space ratio, amplitude, waveform shape etc.

Fig. 2 illustrates for the AC that uses in diving EM field generator 5 to DC converter 18 and handover module.Provide three-phase power (for example 4500 volt) to AC to DC converter 18 by stube cable 10.AC to 18 pairs of three-phase input rectifyings of DC converter on bus-

bar

54 and 56, to produce the positive and negative DC signal of dual voltage.Then switch the DC signal of generation on the bus-

bar

54,56 on waveform output electrode group 60, to produce the drive waveform signal by handover module 19.

AC comprises three-phase step-down device 42 and bridge rectifier 52 to DC converter 18.Provide three-phase power from stube cable 10 to the elementary winding of three-phase step-down device 42.Three-phase step-down device 42 provides three

output phases

46,48,50.Every AC signal (for example 47 volts) that provides voltage to reduce mutually to these three

output phases

46,48,50.

Bridge rectifier 52 comprises respectively being three groups of two diodes, and each group comprises two diodes that are connected in series between the bus-bar 54,56.Each

output phase

46,48,50 drives pair of diodes separately at the tie point place of two diodes.Diode on the whole cycle of three-phase supply in the pair of diodes alternately is driven into conducting state, thereby at the DC signal that produces positive polarity on first bus-bar 54 and on second bus-bar 56, produce the DC signal of negative polarity.

Handover module 19 is made up of 62, the 63 and second pairs of

switches

64,65 of first pair of switch that respectively are connected in series between the bus-bar 54,56.The right switch room tie point of switch provides a waveform output electrode 60.Can use the spike that comprises one or more diode (not shown) to suppress circuit, produce the induction back-emf so that operating switch prevented switch at 62,63,64,65 o'clock.In order to produce the drive waveform signal on to 60, press each

switch

62,63,64,65 of predefined procedure operating switch centering in the waveform output electrode.

A kind of selection is to produce three condition drive waveform signal by generate forward current, inverse current and zero current between waveform output electrode 60.By thereby the switch 63 of the closed first switch centering and the switch 64 of second switch centering cause electric current can generate forward current by first direction is mobile between waveform output electrode 60 simultaneously.Obtain zero current by guaranteeing that all switches 62,63,64,65 are all opened.Thereby causing electric current to flow by the direction in contrast to first direction, the switch 65 of switch 62 by the closed first switch centering simultaneously and second switch centering can generate inverse current between waveform output electrode 60.

The waveform output electrode is to 60 copper electrodes that can be connected to a pair of formation antenna 20.In the use, these copper electrodes are used for that electric current is flow to seawater and produce the EM field with the response wave shape drive signal.This antenna 20 is equal to low resistance, high inductive load.

Fig. 3 illustrates the handover module 19 that uses in the diving EM field generator 5 ' and transient suppressor.This handover module 19 ' can be used to substitute the top handover module 19 that Fig. 2 is mentioned with transient suppressor.

Handover module 19 ' 80,81 and second switch mosfet is constituted 82,83 by first switch mosfet that respectively is connected in series between the bus-bar 54,56.Tie point between the switch mosfet of every pair of switch mosfet provides a waveform output electrode.In addition, each

switch mosfet

80,81,82,83 of these switch mosfet centerings is connected with separately

diode

68,69,70,71 in parallel, and MOSFET produced the induction back-emf when this prevented

switch mosfet

80,81,82,83 operations.In order to produce the drive waveform signal on to 60, apply the control module 16 of control signal each

switch mosfet

80,81,82,83 by gate pole according to predetermined sequential operation switch mosfet centering to switch

mosfet

80,81,82,83 in the waveform output electrode.

First end of the source electrode of each

switch mosfet

80,81,82,83 and transient voltage suppressor separately 85,87,89,91 is connected and with Kelvin's

source connector

43,45,47,49 correspondence, first lead-in wire is connected.Second end of the gate pole of each

switch mosfet

80,81,82,83 and transient voltage suppressor separately 85,87,89,91 is connected and is connected with correspondence second lead-in wire of Kelvin's

source connector

43,45,47,49.Kelvin's source connector is connected to control module 16 to the source electrode and the gate pole of 43,45,47,49 each

corresponding switch mosfet

80,81,82,83.

Control module 16 can be for producing the independent unit of predetermined drive waveform Signal Spacing operation, perhaps can be remote command, for example by providing signal from waterborne vessel 4.

The solid-state switch of employing such as switch mosfet has the benefit that reliable high-speed switch is provided.In addition, in the

switch mosfet

80,81,82,83 one or more can with other semiconductor switch device for example IGBT (igbt) and/or with a plurality of be connected in parallel and have switch mosfet or other semiconductor switch that public gate pole connects substitute, to improve the electric current handling capacity of switch.

Transient suppressor by one group independently

transient suppressor

84,86,88,90,92 form and be designed to make handover module 19 ' under the situation of not

damaging switch mosfet

80,81,82,83, switch high power signals (for example greater than 10 kilowatts).Each transient suppress 84,86,88,90,92 provides the character according to transient effect to be transferred to the straining element of characteristic frequency or particular frequency range.For example behind stube cable 10, bus-

bar

54 and 56 etc. the inductance, determine the value that each components and parts of transient suppressor are taked in the characteristic of analyzing power transmission system.The example value that adopts in a kind of design is: C4=C5=6800 μ F, 385V; C3=30 μ F, 250V; C1=C2=1 μ F; D1=85A; R3=R4=10 Ω; 500W; And R1=1 Ω, 2W.Should note to be provided with the such transient suppress of many groups to improve total transition rejection characteristic of diving EM field generator 5.

Fig. 4 schematically illustrates the EM field that is used for the seabed electromagnetic survey and produces system 9.The EM field produces system 9 and comprises power supply 6 and control module 8.GPS Adjustment System clock 11 can be operable to control module 8 and be connected.GPS Adjustment System clock 11, power supply 6 and control module 8 typically are arranged in waterborne vessel 4.The EM field produces system 9 and comprises that also the controller 16 that typically is arranged in underwater ship 12, data collection module 106, AC are to DC converter 18, handover module 19 and antenna 20.

Provide AC electric power from 6 couples of AC of power supply to DC converter 18 by stube cable 10.AC produces the one or more DC signals that can then be switched by handover module 19 to DC converter 18, thereby is used for the drive waveform signal of driven antenna 20 EM is provided the field to provide.

Control module 8 comprises synchronizer 100 and controller waterborne 102.Controller 102 waterborne provides central authorities' control and data logging, and it can select for use the computer system for networking together to provide by one or more.The low-frequency clock signal that controller 102 waterborne and GPS Adjustment System clock 11 produce is synchronous, for example per minute and/or p.s..Controller 102 waterborne utilizes the synchronous EM of this low-frequency clock signal field to produce the various controller clocks of system 9.Use GPS Adjustment System clock 11 to become absolute time accurately to the clock setting of each controller.

GPS Adjustment System clock 11 can be operable in synchronizer 100 and to produce synthetic high frequency clock signal, for example such as the frequency between 1024 hertz 1 to 5 kilo hertz.This high frequency clock signal by EM field generation system be used as overall major clock and guarantee between the synchronous operation between various controller clocks low time drift (for example＜10 ^-20).

On optical fiber link 101a, send this high frequency clock signal through stube cable 10.Optical fiber link 101a comprises based on the transmitter module 94a of laser diode and light receiver module 95a.Light receiver module 95a provides this high frequency clock signal to the underwater manipulator 104 and the status register 108 that constitute controller 16 parts.Also provide this high frequency clock signal to data collection module 106 by optical fiber link 101a.

Optical fiber link 101b provides the control communication link to underwater manipulator 104.Controller 102 waterborne communicate by letter with bottom controller 104 by optical fiber link 101b and notify bottom controller 104 it can expect when receive synchronizing signal.Optical fiber link 101b also is used for other control communication, for example to the layout of the waveform that will generate.The various data that can also utilize optical fiber link 101b loopback bottom controller 104 to collect.Can be combined into single link to optical fiber link 101b and 101c.For example, it is multiplexed to utilize single fiber to carry out.

In nominal operation, the operation timing of handover module 19 depends on the synthetic high frequency clock signal that sends to underwater manipulator 104 and status register 108.104 pairs of clock pulse counts of underwater manipulator, and its indicating status register 108 is carved the handover configurations that changes handover module in due course when the suitable counting of the switching state that will change the drive waveform signal approaches (by the waveform decision of programming).This provides switching timing accurately, because carry out blocked operation as the status register 108 of a stand-by period fixed logic device under the stand-by period of knowing between blocked operation and this high frequency clock signal.

If there is not status register 108, bottom controller 104 direct control switch modules 19, even 104 true-time operations of bottom controller, the consistance of switching the stand-by period can disappear and on average go up the stand-by period can be increased.In addition, adopt status register 108 that underwater manipulator 104 is being communicated by letter on optical fiber link 101b under the timing that does not influence blocked operation, for example utilize serial or packet-based communication protocol.

Synchronizer 101 sends this high frequency clock signal on optical fiber link 101a.This also can be used for making the clock of bottom controller related with gps time.Controller 102 waterborne arrives absolute time by GPS Adjustment System clock setting, but is not high-precision.Controller 102 waterborne is accurate to is enough to determine when next low frequency synchronisation signal is predefined in.Controller 102 waterborne is set to synchronizer 100 at the time changing high frequency clock signal that receives low frequency synchronisation signal.Underwater manipulator 104 is construed to one to the change in the high frequency clock signal and immediately or after preset time its counter reset is become zero instruction.Thereby utilize the zero count of Absolute Time Synchronization bottom control 104.

The EM field produces system 9 and comprises data collection module 106.Data collection module 106 can be configured to collection system data (for example, sending the detailed measurements of waveform, diagnostic message etc.) or environmental data (for example, bottom contour, ocean temperature information, seawater conductivity data etc.).Utilize absolute time and/or utilize high frequency clock signal to add time stamp the data that data collection module 106 obtains.These data can send to underwater manipulator 104 or send to controller 102 waterborne through optical fiber link 101c.

When the data sampling of

underwater manipulator

104 or 102 pairs of data collection modules 106 of controller waterborne, can utilize the absolute time that provides according to GPS Adjustment System clock 11 to add time stamp immediately.Can be by one or more counter keeps track absolute times to high frequency clock cycle and/or synchronizing signal (for example synchronizing signal that sends as the variation in the high frequency clock signal) counting.The content of each counter can be served as time stamp then.This means, in case the data that obtain on the compromise possibly underwater manipulator of considering 104 of typically dried up its data space of going on board quite far away and reliability are gathered and are added time stamp, can utilize packet-based host-host protocol for example to send these data in Ethernet long distance ground on fiber optic cables, data added-time stamp is guaranteed any propagation delay time, for example the intrinsic variable time delay of packet-based host-host protocol can not damage data.

Fig. 5 schematically illustrates the drive waveform signal 103 that diving EM field generator 5 produces.This drive waveform signal 103 be by optionally switch two DC signal+V and-three condition square wave that V produces is approximate.The once circulation of this waveform comprises wherein DC signal+V is switched to phase one t in the output of EM field generator 5 _PosIts back and then wherein two DC signals be not provided to zero-signal stage t in the output of EM field generator 5 ₀Then the output of EM field generator 5 is at t _NegStage switches to-V on, then with another zero-signal stage t ₀Finish current circulation.

Each embodiment that the insider understands this paper explanation only is an example, and many variants and modifications are tangible.In addition, the insider can be appreciated that antenna is equal to any device of realizing electric dipole, and term " square wave " is not only to be equal to the pure square wave that only switches between two level.Will also be understood that the present invention can be applied to explore for example big lake of fresh water equivalently, thus the seabed, and it is restriction that the quoting of seawater etc. should not become.

List of references

[1]GB?2?381?137A

Claims

1. diving electromagnetism (EM) field generator that is used for the seabed electromagnetic survey comprises:

Can be operable to from the AC input and produce the AC of first and second DC output to the DC converter;

Can be operable to by optionally switch the handover module that described DC output produces the drive waveform signal by means of a plurality of switches;

Surge protecting circuit, described surge protecting circuit is included in one group of transient suppressor in parallel in the described first and second DC outputs, each transient suppressor provide be tuned to the inhibition of characteristic frequency or frequency range, protection is provided for described switch at the induction back electromotive force that is produced when the described switch of operation thus; And

Can be operable to the antenna that generates an electromagnetic field in response to described drive waveform signal.

2. according to the diving electromagnetic field generator of claim 1, wherein, this AC can be operable to from three-phase AC input to the DC converter and produce DC output.

3. according to the diving electromagnetic field generator of claim 1, wherein, described switch is a semiconductor switch.

4. according to the diving electromagnetic field generator of claim 3, wherein, each semiconductor switch has the transient voltage suppressor that is connected between its source electrode and the grid.

5. according to the diving electromagnetic field generator of claim 3, wherein, described semiconductor switch is MOSFET or IGBT.

6. according to any one the diving electromagnetic field generator among the claim 1-5, wherein, described surge protecting circuit comprises one or more diodes.

7. according to the diving electromagnetic field generator of claim 6, wherein, the respective diode in each in the described switch and the described diode is connected in parallel.

8. according to any one the diving electromagnetic field generator among the claim 1-5, described transient suppressor has such electric capacity, diode and/or resistance, and the value of wherein said electric capacity, diode and/or resistance is selected according to its corresponding characteristic frequency or frequency range.

9. according to any one the diving electromagnetic field generator among the claim 1-5, wherein, described AC also can be operable to the DC converter and produce at least one additional DC output, so that a plurality of DC output is arranged, and described handover module also can be operable to by optionally switching described a plurality of DC and exports and produce the drive waveform signal.

10. according to any one the diving electromagnetic field generator among the claim 1-5, also comprise controller, thereby its selectivity that can be operable to the described handover module of control is switched and is produced the drive waveform signal.

11. according to the diving electromagnetic field generator of claim 10, wherein, this controller can be operable to the reception external synchronization signal, and responds the operation that this signal is controlled this handover module, thereby starts the generation of drive waveform signal.

12. according to the diving electromagnetic field generator of claim 10, wherein, this controller can be operable to the reception external command signal, and controls described handover module, thereby depends on this external command signal and produce a kind of in the multiple predetermined drive waveform signal.

13. any one the diving electromagnetic field generator according among the claim 1-5 also can be operable to the reception external timing signal.

14. according to the diving electromagnetic field generator of claim 13, wherein, described handover module can be operable to described external timing signal and synchronously generate the drive waveform signal.

15. any one the diving electromagnetic field generator according among the claim 1-5 also comprises data collection module.

16. according to any one the diving electromagnetic field generator among the claim 1-5, also can be operable to the reception external timing signal, and also comprise data collection module, and wherein, described data collection module can be operable to and receive this external timing signal and utilize the data of this data collection module being collected from the time stamp of this external timing signal generation to add time stamp.

17. according to the diving electromagnetic field generator of claim 15, wherein, described data collection module also can be operable to the data that described data collection module is collected and send to marine equipment from underwater ship.

18. electromagnetism (EM) generation system that is used for the seabed electromagnetic survey comprises:

The diving electromagnetic field generator, it comprises: can be operable to from the AC input and produce the AC of first and second DC output to the DC converter; Can be operable to by optionally switch the handover module that described DC output produces the drive waveform signal by means of a plurality of switches; Surge protecting circuit, described surge protecting circuit is included in one group of transient suppressor in parallel in the described first and second DC outputs, each transient suppressor provide be tuned to the inhibition of characteristic frequency or frequency range, protection is provided for described switch at the induction back electromotive force that is produced when the described switch of operation thus; Can be operable to the antenna that generates an electromagnetic field in response to described drive waveform signal; And thereby the selectivity that can be operable to the described handover module of control is switched the controller that produces the drive waveform signal;

Can be operable to the power supply to the coupling of DC converter with the AC of described electromagnetic field generator; And

Can be operable to the control module with the coupling of the controller of described diving electromagnetic field generator, wherein this control module can be operable to the drive waveform signal that control is used to drive described antenna.

19. produce system according to the electromagnetic field of claim 18, wherein, described control module can be operable to and the coupling of HA Global Positioning Satellite (GPS) receiver, and can be operable to and GPS sender signal clocking synchronously.

20. the electromagnetic field according to claim 19 produces system, wherein this control module can be operable to provides described clock signal to described controller.

21. the electromagnetic field according to claim 19 produces system, wherein this control module can be operated the paired data collection module described clock signal is provided.

22. produce system according to the electromagnetic field of claim 21, wherein this data collection module can be operable to utilization and from the time stamp that this clock signal generates the data of collecting added time stamp.

23. the electromagnetic field according to claim 13 produces system, wherein this control module can be operable to the controller coupling that utilizes fiber optic cables and this diving electromagnetic field generator.

24. a generation is used for the method for electromagnetism (EM) field of seabed electromagnetic survey, comprising:

AC is provided signal;

Produce the DC signal from this AC signal in first and second DC output;

Produce the drive waveform signal by using a plurality of switches of protecting by surge protecting circuit to switch described DC signal, wherein said surge protecting circuit is included in one group of transient suppressor in parallel in the described first and second DC outputs, each transient suppressor provide be tuned to the inhibition of characteristic frequency or frequency range, protection is provided for described switch at the induction back electromotive force that is produced when the described switch of operation thus; And

Utilize this drive waveform signal to drive electric dipole to generate an electromagnetic field.

25. the method for claim 24 also comprises: produce at least one additional DC signal,, and produce the drive waveform signal by optionally switching described a plurality of DC signal so that a plurality of DC signals are arranged.

26. the method for claim 24, described switch is a semiconductor switch.

27. the method for claim 26, wherein, each semiconductor switch has the transient voltage suppressor that is connected between its source electrode and the grid.

28. the method for claim 26, wherein, described semiconductor switch is MOSFET or IGBT.

29. the method for arbitrary claim in the claim 24 to 28, wherein, surge protecting circuit comprises one or more diodes.

30. the method for claim 29, wherein, the respective diode in each in the described switch and the described diode is connected in parallel.

31. the method for arbitrary claim in the claim 24 to 28, described transient suppressor has such electric capacity, diode and/or resistance, and the value of wherein said electric capacity, diode and/or resistance is selected according to its corresponding characteristic frequency or frequency range.

32. the method for the arbitrary claim in the claim 24 to 28 comprises: the generation of the drive waveform signal that produces at the diving electromagnetic field generator and synchronous from the clock signal that provides waterborne.